#include <iostream>

using namespace std;

//int main()
//{
//	const int yincunToyincu = 12;
//
//	int height = 0;
//	cin >> height;
//	cout << height / yincunToyincu << " " << height % yincunToyincu << endl;
//
//	return 0;
//}

//int main()
//{
//	const int inToc = 12;
//	int inc = 0;
//	int incun = 0;
//	cin >> inc >> incun;
//	int bang = 0;
//	cin >> bang;
//	double height = (inc * inToc + incun) * 0.0254;
//	double weight = bang / 2.2;
//	double BMI = weight / (height * height);
//	cout << BMI << endl;
//	return 0;
//}


//int main()
//{
//	const int dutoFen = 60;
//	const int fentoMiao = 60;
//	double du = 0;
//	double fen = 0;
//	double miao = 0;
//	cin >> du >> fen >> miao;
//	double value = du + fen / dutoFen + miao / fentoMiao / dutoFen;
//	cout << value;
//	return 0;
//}


//int main()
//{
//	long miao = 0l;
//	const int tiantohour = 24;
//	const int hoursTominue = 60;
//	const int minutTomiao = 60;
//	cin >> miao;
//	int day = miao / (tiantohour * hoursTominue * minutTomiao);
//	miao %= (tiantohour * hoursTominue * minutTomiao);
//	int hours = miao / (hoursTominue * minutTomiao);
//	miao%= (hoursTominue * minutTomiao);
//	int minute = miao / minutTomiao;
//	miao %= minutTomiao;
//	cout << day << " " << hours << " " << minute << " " << miao << endl;
//
//
//	return 0;
//}


//int main()
//{
//	long long worldPeople;
//	cin >> worldPeople;
//	long long us;
//	cin >> us;
//	cout << (us / (double)worldPeople)*100 <<"%" << endl;
//
//	return 0;
//}


//int main()
//{
//	float inli = 0;
//	cin >> inli;
//	float jialun = 0;
//	cin >> jialun;
//	cout << inli / jialun << endl;
//	float km = 0;
//	float sheng = 0;
//	cout << (sheng / km) * 100 << endl;
//
//	return 0;
//}

int main()
{
	const float kmtomile = 62.14;
	const float jialuntoshneg = 3.785;
	float youhao = 0;
	cin >> youhao;
	float km1sheng = kmtomile/(youhao/jialuntoshneg);
	cout << km1sheng << endl;


	return 0;
}